Institute of Astronomy

Hydrogen Epoch of Reionization Array

SpeakerTalk DateTalk Series
Chris Carilli (Astrophysics, Cambridge)20 October 2016Institute of Astronomy Colloquia


The Hydrogen Epoch of Reionization Array (HERA) is a low frequency experiment designed to study cosmic reionization using the 21cm hyperfine line of neutral hydrogen. Reionization corresponds to the last 'cosmic phase transition', when the neutral gas that pervaded the Universe post-recombination is reionized by the light from the first stars and black holes, a few hundred million years after the Big Bang. Cosmic reionization is one of the last frontiers in cosmology and studies of large scale structure formation. The HI 21cm line has the potential to be the most incisive probe of the physical processes driving reionization. I will briefly summarize the latest measurements of the evolution of the neutral fraction of the intergalactic medium (IGM) during reionization. I will then review the physics, techniques, and challenges of HI 21cm cosmology, and present the latest limits on the HI 21cm signal from the early Universe. Limits from experiments such as PAPER in South Africa, are reaching astrophysically relevant sensitivities, and setting interesting constraints on early heating of the IGM. I will present an update of the HERA project, including design, capabilities, and construction status, as well as first light data from the array.